Question

您好我有一个名为student_subject_table的mysql表：

+----+-------------+---------------------+ 
| id | student_id  | subject             | 
+----+-------------+---------------------+ 
|  1 |           7 | math                | 
|  2 |           7 | physics             |  
|  3 |           7 | chemistry           |  
|  8 |           8 | math                | 
|  9 |           8 | physics             | 
| 10 |           8 | chemistry           | 
| 11 |           8 | biology             |  
+----+-------------+---------------------+

我试图让那些只有数学，物理和化学成分的学生ids。

我在条款中试过：

 select student_id
 from student_subject table
 where
   subject in ('math', 'physics', 'chemistry')
 GROUP BY (student_id)

正如预期的那样，我将7和8作为student_id。在上表中我只需要student_id = 7.

在mysql中我有什么办法吗？

请帮忙。

Answer 1

您可以使用此查询：

@Bean
public CorsFilter corsFilter() {

    UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
    CorsConfiguration config = new CorsConfiguration();
    config.setAllowCredentials(true); // you USUALLY want this
    // likely you should limit this to specific origins
    config.addAllowedOrigin("*"); 
    config.addAllowedHeader("*");
    config.addAllowedMethod("GET");
    config.addAllowedMethod("POST");
    config.addAllowedMethod("PUT");
    source.registerCorsConfiguration("/logout", config);
    return new CorsFilter(source);
}

select student_id from student_subject table group by student_id having SUM(subject IN ('math', 'physics', 'chemistry')) = COUNT(DISTINCT subject) AND COUNT(DISTINCT subject)=3将为3
SUM(subject IN ('math', 'physics', 'chemistry'))将为学生7为3，为学生8为

如果COUNT(DISTINCT subject)是唯一的，您可以将(student_id, subject)替换为COUNT(DISTINCT ...)。

只返回学生7。

Answer 2

使用DISTINCT条款

SELECT DISTINCT student_id 
FROM student_subject_table 
WHERE subject IN ('math', 'physics', 'chemistry') 
GROUP BY (student_id);

Mysql选择只在列中具有指定值的行

2 个答案: